The present invention relates generally to read/write drives, and more particularly to drive loaders which assist in loading and securing media cartridges within read/write drives.
A schematic illustration of a cartridge handling system 10 is shown in FIG. 1. A cartridge handling system 10 typically includes a plurality of cartridge storage locations 12, one or more read/write drives 14, and at least one cartridge handling apparatus 16 which is adapted to transfer media cartridges 18 among the cartridge storage locations 12 and drives 14.
Many types of media cartridges have a centrally-located hub which must be secured to a drive spindle in order for the media to spool and the cartridge to be read and/or written on. Specifically, the teeth of the cartridge hub must engage the teeth of the drive spindle. Such media cartridges include most tape cartridges such as DLT tape cartridges manufactured by Quantum Corporation of Threwsbury, Mass. To assist in loading, aligning, and securing a cartridge within a drive, as well as disengaging and unloading a cartridge, a drive loader may be provided which includes a cartridge locking mechanism and an overcentering mechanism. The cartridge locking mechanism may be any mechanism known in the art that, when closed, secures a cartridge within a drive so that the cartridge may be read and/or written to by the drive. When open, the cartridge locking mechanism allows the cartridge to be loaded into or unloaded from the drive. For example, the cartridge locking mechanism found in a Quantum DLT drive consists of a door which closes behind a cartridge, latches which engages notches in the cartridge, and a drive spindle which engages with the cartridge hub. However, the present invention may be utilized with any drive loader which comprises an overcentering mechanism such as described herein.
Referring to FIGS. 2 and 3, the overcentering mechanism 20 of a drive loader 19 may basically consist of a spring-loaded, pivotable drive loader actuator shaft 22 which pivots around an axis AA in order to actuate a cartridge locking mechanism 23 (only door of mechanism is shown) upon loading and unloading of a cartridge. An overcentering mechanism 20 may be found on Quantum DLT drives (Model Nos. 4000, 7000, and 8000, for example). A drive having an overcentering mechanism is shown and described in U.S. Pat. No. 5,774,301, which is hereby incorporated by reference for all that is contained therein.
When an overcentering mechanism is closed slowly rather than being allowed to snap shut with some force, the end result may be a drive misload. The misload occurs because the teeth on the cartridge hub have not been properly engaged with the teeth on the drive spindle. The cartridge locking mechanism can more reliably secure a cartridge hub on a drive spindle when the cartridge is jarred by snapping closed the overcentering mechanism with some force rather than closing the overcentering mechanism slowly and gently. The overcentering mechanism could be closed forcefully, yet manually, by attaching a handle to the actuator shaft in order to rotate the shaft by hand as described below with reference to FIGS. 4 and 5. However, in cartridge handling systems it is most preferable to close the overcentering mechanism remotely rather than manually.
One way to close the overcentering mechanism remotely is shown in U.S. Pat. No. 5,774,301, incorporated by reference above. This patent discloses an overcentering mechanism with a handle attached to the drive loader actuator shaft that is operated remotely by the cartridge handling apparatus. A problem with this design is that the handle typically requires a substantial amount of force to operate which must be provided by the cartridge handling apparatus lift system, thus requiring a more complex and expensive lift system for the cartridge handling apparatus. Another problem is that the cartridge handling apparatus is used for a purpose other than to simply retrieve and transport cartridges, that is, operating the handle. Specifically, the cartridge handling apparatus must be positioned in front of the drive while the cartridge is being secured within the drive, rather than simply ejecting the cartridge and then immediately traveling to another cartridge storage location or drive while the cartridge is being loaded into the drive.
Current designs may utilize a motor-driven gear assembly operatively connected to the drive loader actuator shaft to remotely activate the overcentering mechanism. Such a gear assembly 30 is shown in FIG. 6 and described in further detail below. However, this gear assembly 30 closes the overcentering mechanism slowly and gently rather than quickly with some force.
Thus, it is an object of the present invention to provide a drive loader which allows the cartridge locking mechanism to be remotely and quickly snapped closed, which is most preferable when the drive is located in an automated cartridge handling system.
It is also an object of the present invention to provide a drive loader with a motor-driven gear assembly that quickly snaps closed the cartridge locking mechanism.
It is also an object of the present invention to provide a split compound gear assembly for a drive loader which allows the overcentering mechanism actuator shaft to freely rotate to a closed position.
It is a further object of the present invention to provide a cartridge handling system which includes a drive having a drive loader with a split compound gear assembly.
It is yet another object of the present invention to provide a method for quickly closing a cartridge locking mechanism on a drive loader with some force.
The present invention is directed to a split compound gear assembly for a drive loader of the type having an overcentering mechanism with a drive loader actuator shaft. The gear assembly may comprise a split compound gear having an outer member and an inner member. The outer member may comprise an outer, larger gear, a free rotation area recessed from an outer annular flange, and a stop portion extending from the recessed free rotation area. The outer member may further comprise an inner annular flange adapted to rotatingly receive the inner member. The inner member may comprise an inner, smaller gear and an extending portion. The inner member is freely rotatable within the free rotation area of the outer member until the extending portion of the inner member abuts the stop portion of the outer member. The inner member is rotatable with the outer member when the extending portion abuts the stop portion. The split compound gear assembly may further comprise a sector gear which engages the inner gear of the split compound gear. The sector gear may comprise a bore which is adapted to receive the drive loader actuator shaft. The split compound gear assembly may further comprise a drive gear operably connected to a motor and a first compound gear engaging the drive gear. The first compound gear is not a split compound gear. Instead, the first compound gear comprises an outer, larger gear attached to an inner, smaller gear which may be integrally formed with the outer gear. The inner, smaller gear the first compound gear engages the outer, larger gear of said second compound gear.
The drive loader actuator shaft comprises an open position, an overcenter position, and a closed position. The shaft travels a first angular distance from the overcenter position to the closed position. The maximum angular distance between the outer member stop portion and the inner member extending portion is preferably larger than the first angular distance.
The present invention is also directed to a cartridge handling system comprising a plurality of cartridge storage locations. The system also includes at least one read/write drive comprising a drive loader having an overcentering mechanism having a drive loader actuator shaft which actuates a cartridge locking mechanism. The system further comprises a split compound gear assembly for the drive loader of the type described above.
The present invention is also directed to a method for closing a cartridge locking mechanism on a drive loader. The drive loader is of the type having an overcentering mechanism with an actuator shaft and a biasing member which biases rotation of the shaft to a closed position. The method comprises the initial step of providing a motor-driven split compound gear assembly such as the assembly described above. The method further comprises using said motor-driven split compound gear assembly to rotate the actuator shaft in a first rotational direction from an open position, whereby the cartridge locking mechanism is open, to an overcenter position. This step may involve remotely sending a signal to the split compound gear assembly to rotate the split compound gear in a second rotational direction, and then rotating the split compound gear in a second rotational direction until the inner member contacts the stop portion of the outer member. The split compound gear continues to rotate in the second rotational direction, whereby the inner member and the outer member rotate together, at least until the actuator shaft is in the overcenter position. The method further comprises the step of allowing the actuator shaft to rotate independently of the motor-driven split compound gear assembly in the first rotational direction from the overcenter position to the closed position such that the overcentering mechanism is quickly snapped closed. This step may involve allowing the inner member to disengage from the stop portion and slidingly (i.e., freely) rotate on the outer member in the second rotational direction.